OTHER ANSWERS

Typically making changes to any of the layout options in OpenCart is going to be done through your theme files. You would more than likely want to modify the CSS stylesheet files to make the style that you'd like to use. Your theme files should be found in [/catalog/view/theme] and a folder called [default] should be holding all your default files.

Normally with the type of listing that you're talking about that would be an unordered list, with list items inside of it. With CSS you can change the properties of the (li) elements to behave in different ways to create more than 1 column of info. It would look something like this in your CSS stylesheet: